It is known to prepare acyloxy aromatic carboxylic acids, e.g., 4-acetoxybenzoic acid (4-ABA), by reacting a phenolic compound, e.g., phenol, with an alkali metal hydroxide, e.g., potassium hydroxide, to form the alkali metal salt of the phenolic compound, e.g., potassium phenoxide, and reacting the salt with carbon dioxide in a Kolbe-Schmitt reaction followed by acidic work-up to form a hydroxy aromatic acid, e.g., 4-hydroxybenzoic acid (4-HBA). The acid is then acylated with an acylating agent, e.g., acetic anhydride, to form the acyloxy aromatic carboxylic acid, e.g., 4-ABA. A substantial disadvantage of this process is the necessity to neutralize the hydroxy aromatic carboxylate salt resulting in the formation of an alkali metal salt which must be separated and disposed of.
The preparation of hydroxy aromatic ketones by the Fries rearrangement of aromatic esters is well-known in the art. Thus, Lewis, U.S. Pat. No. 2,833,825 shows the rearrangement of phenyl or other aromatic esters to acylphenols or other hydroxy aromatic ketones using anhydrous hydrogen fluoride as catalyst. The examples of this patent are limited to the rearrangement of esters of higher fatty acids with the yields ranging from 55 to 95%.
Simons et al., Journal of the American Chemical Society, 62, 485 and 486 (1940), show the use of hydrogen fluoride as a condensing agent for various rearrangements and at page 486 show the Fries rearrangement of phenyl acetate to obtain p- hydroxyacetophenone.
Dann and Mylius in a dissertation included as part of a series of Reports from the Institute for Applied Chemistry of the University of Erlangen, Annalen der Chemie, 587, 1 to 15, (1954) show the rearrangement of phenyl acetate in hydrogen fluoride to 4-hydroxyacetophenone, with a maximum yield of 81% after 24 hours of reaction time, and report a yield of 92% stated to be obtained by K. Weichert as reported in Angewandte Chemie, 56, 338 (1943). However, Dann and Mylius suggest that the difference in yields may be at least partly due to the previous ignoring by Weichert of the accompanying 2-hydroxyacetophenone. Dann and Mylius also report somewhat lower yields of hydroxy aromatic ketones from rearrangements in hydrogen fluoride of acresol acetate, p-cresol acetate, and guaiacol acetate.
Dann and Mylius also disclose the reaction of phenol and glacial acetic acid in the presence of hydrogen fluoride to produce 4-hydroxyacetophenone in a yield of 61.6%. This reaction may be conventionally characterized as a Friedel-Crafts acetylation of phenol with acetic acid as the acetylating agent.
Simons et al., Journal of the American Chemical Society, 61, 1795 and 1796 (1939), teach the acylation of aromatic compounds using hydrogen fluoride as a condensing agent and in Table 1 on page 1796 show the acetylation of phenol with acetic acid to produce p-hydroxyacetophenone in 40% yield.
Meussdoerffer et al., German Offenlegungsschrift No. 26 16 986 published Oct. 27, 1977 and assigned to Bayer AG, disclose the acylation of phenolic compounds such as phenol itself wth an acyl halide such as acetyl chloride to form hydroxy aromatic ketones.
Khandual et al., J. Indian Chem. Soc., 49, 557-560 (Eng.) (1972), as abstracted in C.A. (1972), 77, 125628g, show the oxidation of acetophenone in 95% acetic acid by manganic acetate to form benzoic acid, and formaldehyde. The oxidation of acetophenone containing ring substituents, e.g., methoxy, is also taught.
Den Hertog et al., Journal of Catalysis, 6, 357-361, (1966), show the manganic acetate catalyzed oxidation of acetophenone and acetophenone containing any various ring substituents such as methyl to benzoic acid and corresponding ring substituted benzoic acids.
Van Helden et al., Rec. Trav. Chim., 80, 57-81,(1961), show the manganese ion-catalyzed oxidations of acetophenone and various ring-substituted acetophenones to the corresponding benzoic acids and the cobalt ion-catalyzed oxidation of acetophenone to benzoic acid.
Misra et al., J. Indian Chem. Soc., 52, 1053-1055 (Eng.) (1975) as abstracted in C.A. (1976), 84, 150041n, show the vanadius catalyzed oxidation of acetophenone and acetophenones containing any of various ring substituents such methoxy.
Nippon Kayaku Co., Ltd. (inventors Susumu Nagao and Toshio Takahashi), Japanese Kokai No. Sho 54(1979) - 109941, discloses and claims the oxidation of esters of m-cresol with oxygen in the presence of a heavy metal salt in a solvent of a low molecular weight fatty acid and/or anhydride. It is clear from the published application that the presence of the acid anhydride was not critical to the reaction.
McKeever and Freimiller, U.S. Pat. No. 2,952,703, teaches the oxidation of acetophenone to benzoic acid with oxygen in the presence of a manganese salt, a carboxylic acid, and nitric acid of from 80.degree.-107.degree. C.
Hull, U.S. Pat. No. 2,673,217, teaches the use of aldehydes as co-reductants in the oxidation reaction.
Crowther et al., U.S. Pat. No. 3,539,592, teach the use of a co-reductant, as for example of an aldehyde, in the substantial absence of metal catalyst.
Other references pertinent to the oxidation of alkyl and acyl side chains to an acid moiety include:
Kato et al., Japanese Patent No. 75 35,066 issued Nov. 13, 1975, as abstracted in C.A. (1976), 85, 5360g; Kobayashi et al., Japanese Patent No. 67 849, issued Jan. 18, 1967, and abstracted in C.A. (1967), 66, 55236Z; and Sangaiah et al., Synthesis, 12, 1018-1019, (1980), all show the transition metal-catalyzed oxidation of p-cresyl acetate to 4-acetoxybenzoic acid; and Aoyama et al., Japanese Patent No. 76 108030, discloses the oxidation of 5-acyloxy-meta-xylene to 5-hydroxyisophthalic acid.